Patent GB-571738-A (GB)
Title: An improved process for making abrasive tools
IPC: B24D18/00
Filed: 1943-12-13
Abstract: 571,738. Abrasive tools. KEELERIC, G. D. Dec. 13, 1943, Nos. 20873 and 20874. Convention dates, Nov. 7, 1942, and June 22, 1943. [Class 60] [Also in Group V] Abrasive articles, for example, grinding- wheels and hones, comprise a body having a working surface to which is secured a layer of metal serving as a bond for abrasive particles, which are partially embedded therein and have their outermost portions all lying in the grinding surface. In the manufacture of a cup wheel, Fig. 7, comprising a body 21 of plastic material having on its working surface 22a a layer of bonding metal 24 carrying the abrasive grains 25 with their outer ends lying in a plane, a hard steel blank 26, Fig. 2, is employed, having a conical part 27 and a flange 28 with a flat upper surface. A soft layer 30, Fig. 5, of metal, preferably lead, is applied to the surface 28 and the abrasive particles are then distributed on the layer 30, and pressed by a block or roller so that they all penetrate the layer to contact with the surface 28 ; in place of metal, the layer 30 may be of plastic material, and electrostatic means may be employed for distributing and orienting the particles. Bonding metal 33, for example, iron, nickel or chromium then is applied, electrolytically, by spraying &c. to enclose the exposed parts of the particles and form a layer of substantial thickness ; this layer with the attached particles then is separated from the blank, leaving the soft layer on the blank, or carrying it with the bonding layer for subsequent removal, by wetting, chemical or electrolytic action, after which the bonding layer may be secured to the tool body. In place of the process last described above, the tool body may be moulded to the bonding layer before its removal from the blank, and in this process, as applied to a side cutting wheel, the blank 34, Fig. 14, with the attached bonding layer 33, is placed in a mould 35, 36, with a central rod .37 and, if required, other rods 38, and plastic material 39 is introduced, compressed by a block 40 in a press and heated to harden the material 39, the blank 34 and the soft layer being removed as described above after extraction of the tool from the. mould; a similar process is employed in the moulding of cup wheels. Edge cutting wheels, having the abrasive particles on the periphery are formed by the use of a ring blank 53, Fig. 13, to the interior of which the soft layer 54 to hold the abrasive particles is applied, the particles being pressed into the layer 54 to contact the ring 53 by a presser shoe or by a spring-pressed roller 61, the ring being supported and rotated by rollers 55 on a plate 56; the ring blank then has the central body of the tool moulded therein in a mould having parts 66, 67, 69, Fig. 19, and the blank 54a and mould parts 66, 67 having registering ribs and recesses 64, 65. A passage 71 may be formed in the presser block 69, or also in those employed for the cup and side cutting wheels, to allow egress of excess of plastic material. Tools with several layers of abrasive may be made by coating a blank with soft material in which the abrasive is then embedded and bonding material applied ; a further soft layer is then applied in which further abrasive is embedded and the process repeated till the desired number of layers is obtained.